Last data update: Mar 21, 2025. (Total: 48935 publications since 2009)
Records 1-16 (of 16 Records) |
Query Trace: Houck K[original query] |
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COVID-19 prevention practices and vaccine acceptability among Hispanic and non-Hispanic households in an agricultural community-Washington, 2020
Ortiz N , Hoffman A , Schnall AH , Clara A , Lilo EA , Lofgren H , Guerrero L , Miller JS , Houck P , Weed N , Monterroso E . Disaster Med Public Health Prep 2024 18 e261 OBJECTIVE: To investigate COVID-19 disparities between Hispanic/Latino persons (H/L) and non-H/L persons in an agricultural community by examining behavioral and demographic differences. METHODS: In September 2020, we conducted Community Assessments for Public Health Emergency Response in Wenatchee and East Wenatchee, Washington, to evaluate differences between H/L and non-H/L populations in COVID-19 risk beliefs, prevention practices, household needs, and vaccine acceptability. We produced weighted sample frequencies. RESULTS: More households from predominately H/L census blocks (H/L-CBHs) versus households from predominately non-H/L census blocks (non-H/L-CBHs) worked in essential services (79% versus 57%), could not telework (70% versus 46%), and reported more COVID-19 cases (19% versus 4%). More H/L-CBHs versus non-H/L-CBHs practiced prevention strategies: avoiding gatherings (81% versus 61%), avoiding visiting friends/family (73% versus 36%), and less restaurant dining (indoor 24% versus 39%). More H/L-CBHs versus non-H/L-CBHs needed housing (16% versus 4%) and food assistance (19% versus 6%). COVID-19 vaccine acceptance in H/L-CBHs and non-H/L-CBHs was 42% versus 46%, respectively. CONCLUSIONS: Despite practicing prevention measures with greater frequency, H/L-CBHs had more COVID-19 cases. H/L-CBHs worked in conditions with a higher likelihood of exposure. H/L-CBHs had increased housing and food assistance needs due to the pandemic. COVID-19 vaccine acceptability was similarly low (<50%) between groups. |
Reported incidence of infections caused by pathogens transmitted commonly through food: Impact of increased use of culture-independent diagnostic tests - Foodborne Diseases Active Surveillance Network, 1996-2023
Shah HJ , Jervis RH , Wymore K , Rissman T , LaClair B , Boyle MM , Smith K , Lathrop S , McGuire S , Trevejo R , McMillian M , Harris S , Zablotsky Kufel J , Houck K , Lau CE , Devine CJ , Boxrud D , Weller DL . MMWR Morb Mortal Wkly Rep 2024 73 (26) 584-593 Reducing foodborne disease incidence is a public health priority. This report summarizes preliminary 2023 Foodborne Diseases Active Surveillance Network (FoodNet) data and highlights efforts to increase the representativeness of FoodNet. During 2023, incidences of domestically acquired campylobacteriosis, Shiga toxin-producing Escherichia coli infection, yersiniosis, vibriosis, and cyclosporiasis increased, whereas those of listeriosis, salmonellosis, and shigellosis remained stable compared with incidences during 2016-2018, the baseline used for tracking progress towards federal disease reduction goals. During 2023, the incidence and percentage of infections diagnosed by culture-independent diagnostic tests (CIDTs) reported to FoodNet continued to increase, and the percentage of cases that yielded an isolate decreased, affecting observed trends in incidence. Because CIDTs allow for diagnosis of infections that previously would have gone undetected, lack of progress toward disease reduction goals might reflect changing diagnostic practices rather than an actual increase in incidence. Continued surveillance is needed to monitor the impact of changing diagnostic practices on disease trends, and targeted prevention efforts are needed to meet disease reduction goals. During 2023, FoodNet expanded its catchment area for the first time since 2004. This expansion improved the representativeness of the FoodNet catchment area, the ability of FoodNet to monitor trends in disease incidence, and the generalizability of FoodNet data. |
Preliminary incidence and trends of infections caused by pathogens transmitted commonly through food - Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2022
Delahoy MJ , Shah HJ , Weller DL , Ray LC , Smith K , McGuire S , Trevejo RT , Scallan Walter E , Wymore K , Rissman T , McMillian M , Lathrop S , LaClair B , Boyle MM , Harris S , Zablotsky-Kufel J , Houck K , Devine CJ , Lau CE , Tauxe RV , Bruce BB , Griffin PM , Payne DC . MMWR Morb Mortal Wkly Rep 2023 72 (26) 701-706 Each year, infections from major foodborne pathogens are responsible for an estimated 9.4 million illnesses, 56,000 hospitalizations, and 1,350 deaths in the United States (1). To evaluate progress toward prevention of enteric infections in the United States, the Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for laboratory-diagnosed infections caused by eight pathogens transmitted commonly through food at 10 U.S. sites. During 2020-2021, FoodNet detected decreases in many infections that were due to behavioral modifications, public health interventions, and changes in health care-seeking and testing practices during the COVID-19 pandemic. This report presents preliminary estimates of pathogen-specific annual incidences during 2022, compared with average annual incidences during 2016-2018, the reference period for the U.S. Department of Health and Human Services' Healthy People 2030 targets (2). Many pandemic interventions ended by 2022, resulting in a resumption of outbreaks, international travel, and other factors leading to enteric infections. During 2022, annual incidences of illnesses caused by the pathogens Campylobacter, Salmonella, Shigella, and Listeria were similar to average annual incidences during 2016-2018; however, incidences of Shiga toxin-producing Escherichia coli (STEC), Yersinia, Vibrio, and Cyclospora illnesses were higher. Increasing culture-independent diagnostic test (CIDT) usage likely contributed to increased detection by identifying infections that would have remained undetected before widespread CIDT usage. Reducing pathogen contamination during poultry slaughter and processing of leafy greens requires collaboration among food growers and processors, retail stores, restaurants, and regulators. |
Demographic and clinical characteristics of mpox in persons who had previously received 1 dose of JYNNEOS vaccine and in unvaccinated persons - 29 U.S. Jurisdictions, May 22-September 3, 2022
Farrar JL , Lewis NM , Houck K , Canning M , Fothergill A , Payne AB , Cohen AL , Vance J , Brassil B , Youngkin E , Glenn B , Mangla A , Kupferman N , Saunders K , Meza C , Nims D , Soliva S , Blouse B , Henderson T , Banerjee E , White B , Birn R , Stadelman AM , Abrego M , McLafferty M , Eberhart MG , Pietrowski M , DeLen SM , Creegan E , Diedhiou A , Wiedeman C , Murray-Thompson J , McCarty E , Marcinkevage J , Kocharian A , Torrone EA , Ray LC , Payne DC . MMWR Morb Mortal Wkly Rep 2022 71 (5152) 1610-1615 As of November 14, 2022, monkeypox (mpox) cases had been reported from more than 110 countries, including 29,133 cases in the United States.* Among U.S. cases to date, 95% have occurred among males (1). After the first confirmed U.S. mpox case on May 17, 2022, limited supplies of JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic) were made available to jurisdictions for persons exposed to mpox. JYNNEOS vaccine was approved by the Food and Drug Administration (FDA) in 2019 as a 2-dose series (0.5 mL per dose, administered subcutaneously) to prevent smallpox and mpox disease.() On August 9, 2022, FDA issued an emergency use authorization to allow administration of JYNNEOS vaccine by intradermal injection (0.1 mL per dose) (2). A previous report on U.S. mpox cases during July 31-September 3, 2022, suggested that 1 dose of vaccine offers some protection against mpox (3). This report describes demographic and clinical characteristics of cases occurring 14 days after receipt of 1 dose of JYNNEOS vaccine and compares them with characteristics of cases among unvaccinated persons with mpox and with the vaccine-eligible vaccinated population in participating jurisdictions. During May 22-September 3, 2022, among 14,504 mpox cases reported from 29 participating U.S. jurisdictions,() 6,605 (45.5%) had available vaccination information and were included in the analysis. Among included cases, 276 (4.2%) were among persons who had received 1 dose of vaccine 14 days before illness onset. Mpox cases that occurred in these vaccinated persons were associated with lower percentage of hospitalization (2.1% versus 7.5%), fever, headache, malaise, myalgia, and chills, compared with cases in unvaccinated persons. Although 1 dose of JYNNEOS vaccine offers some protection from disease, mpox infection can occur after receipt of 1 dose, and the duration of protection conferred by 1 dose is unknown. Providers and public health officials should therefore encourage persons at risk for acquiring mpox to complete the 2-dose vaccination series and provide guidance and education regarding nonvaccine-related prevention strategies (4). |
Reduced risk for Mpox after receipt of 1 or 2 doses of JYNNEOS vaccine compared with risk among unvaccinated persons - 43 U.S. Jurisdictions, July 31-October 1, 2022
Payne AB , Ray LC , Cole MM , Canning M , Houck K , Shah HJ , Farrar JL , Lewis NM , Fothergill A , White EB , Feldstein LR , Roper LE , Lee F , Kriss JL , Sims E , Spicknall IH , Nakazawa Y , Gundlapalli AV , Shimabukuro T , Cohen AL , Honein MA , Mermin J , Payne DC . MMWR Morb Mortal Wkly Rep 2022 71 (49) 1560-1564 As of October 28, 2022, a total of 28,244* monkeypox (mpox) cases have been reported in the United States during an outbreak that has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (1). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series (with doses administered 4 weeks apart), was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and mpox disease (2); an FDA Emergency Use Authorization issued on August 9, 2022, authorized intradermal administration of 0.1 mL per dose, increasing the number of persons who could be vaccinated with the available vaccine supply(†) (3). A previous comparison of mpox incidence during July 31-September 3, 2022, among unvaccinated, but vaccine-eligible men aged 18-49 years and those who had received ≥1 JYNNEOS vaccine dose in 32 U.S. jurisdictions, found that incidence among unvaccinated persons was 14 times that among vaccinated persons (95% CI = 5.0-41.0) (4). During September 4-October 1, 2022, a total of 205,504 persons received JYNNEOS vaccine dose 2 in the United States.(§) To further examine mpox incidence among persons who were unvaccinated and those who had received either 1 or 2 JYNNEOS doses, investigators analyzed data on 9,544 reported mpox cases among men(¶) aged 18-49 years during July 31-October 1, 2022, from 43 U.S. jurisdictions,** by vaccination status. During this study period, mpox incidence (cases per 100,000 population at risk) among unvaccinated persons was 7.4 (95% CI = 6.0-9.1) times that among persons who received only 1 dose of JYNNEOS vaccine ≥14 days earlier and 9.6 (95% CI = 6.9-13.2) times that among persons who received dose 2 ≥14 days earlier. The observed distribution of subcutaneous and intradermal routes of administration of dose 1 among vaccinated persons with mpox was not different from the expected distribution. This report provides additional data suggesting JYNNEOS vaccine provides protection against mpox, irrespective of whether the vaccine is administered intradermally or subcutaneously. The degree and durability of such protection remains unclear. Persons eligible for mpox vaccination should receive the complete 2-dose series to optimize strength of protection(††) (5). |
Incidence of monkeypox among unvaccinated persons compared with persons receiving 1 JYNNEOS vaccine vose - 32 U.S. jurisdictions, July 31-September 3, 2022
Payne AB , Ray LC , Kugeler KJ , Fothergill A , White EB , Canning M , Farrar JL , Feldstein LR , Gundlapalli AV , Houck K , Kriss JL , Lewis NM , Sims E , Smith DK , Spicknall IH , Nakazawa Y , Damon IK , Cohn AC , Payne DC . MMWR Morb Mortal Wkly Rep 2022 71 (40) 1278-1282 Human monkeypox is caused by Monkeypox virus (MPXV), an Orthopoxvirus, previously rare in the United States (1). The first U.S. case of monkeypox during the current outbreak was identified on May 17, 2022 (2). As of September 28, 2022, a total of 25,341 monkeypox cases have been reported in the United States.* The outbreak has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (3). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series with doses administered 4 weeks apart, was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and monkeypox infection (4). U.S. distribution of JYNNEOS vaccine as postexposure prophylaxis (PEP) for persons with known exposures to MPXV began in May 2022. A U.S. national vaccination strategy(†) for expanded PEP, announced on June 28, 2022, recommended subcutaneous vaccination of persons with known or presumed exposure to MPXV, broadening vaccination eligibility. FDA emergency use authorization (EUA) of intradermal administration of 0.1 mL of JYNNEOS on August 9, 2022, increased vaccine supply (5). As of September 28, 2022, most vaccine has been administered as PEP or expanded PEP. Because of the limited amount of time that has elapsed since administration of initial vaccine doses, as of September 28, 2022, relatively few persons in the current outbreak have completed the recommended 2-dose series.(§) To examine the incidence of monkeypox among persons who were unvaccinated and those who had received ≥1 JYNNEOS vaccine dose, 5,402 reported monkeypox cases occurring among males(¶) aged 18-49 years during July 31-September 3, 2022, were analyzed by vaccination status across 32 U.S. jurisdictions.** Average monkeypox incidence (cases per 100,000) among unvaccinated persons was 14.3 (95% CI = 5.0-41.0) times that among persons who received 1 dose of JYNNEOS vaccine ≥14 days earlier. Monitoring monkeypox incidence by vaccination status in timely surveillance data might provide early indications of vaccine-related protection that can be confirmed through other well-controlled vaccine effectiveness studies. This early finding suggests that a single dose of JYNNEOS vaccine provides some protection against monkeypox infection. The degree and durability of such protection is unknown, and it is recommended that people who are eligible for monkeypox vaccination receive the complete 2-dose series. |
COVID-19 Case Investigation and Contact Tracing in Central Washington State, June-July 2020.
Miller JS , Bonacci RA , Lash RR , Moonan PK , Houck P , Van Meter JJ , Butler M , Everson T , Morrison B , Sixberry M , Person A , Oeltmann JE . J Community Health 2021 46 (5) 1-4 OBJECTIVE: To evaluate participation in COVID-19 case investigation and contact tracing in central Washington State between June 15 and July 12, 2020. METHODS: In this retrospective observational evaluation we combined SARS-CoV-2 RT-PCR and antigen test reports from the Washington Disease Reporting System with community case investigation and contact tracing data for 3 health districts (comprising 5 counties) in central Washington State. All 3 health districts have large Hispanic communities disproportionately affected by COVID-19. RESULTS: Investigators attempted to call all referred individuals with COVID-19 (n = 4,987); 71% were interviewed. Of those asked about close contacts (n = 3,572), 68% reported having no close contacts, with similar proportions across ethnicity, sex, and age group. The 968 individuals with COVID-19 who named specific contacts (27% of those asked) reported a total of 2,293 contacts (mean of 2.4 contacts per individual with COVID-19); 85% of listed contacts participated in an interview. CONCLUSIONS: Most individuals with COVID-19 reported having no close contacts. Increasing community engagement and public messaging, as well as understanding and addressing barriers to participation, are crucial for CICT to contribute meaningfully to controlling the SARS-CoV-2 pandemic. |
Age- and treatment-related associations with health behavior change among breast cancer survivors
Anderson C , Sandler DP , Weinberg CR , Houck K , Chunduri M , Hodgson ME , Sabatino SA , White MC , Rodriguez JL , Nichols HB . Breast 2017 33 1-7 OBJECTIVE: The aim of this study was to identify demographic and treatment-related factors associated with health-promoting behavior changes after a breast cancer diagnosis. Changes in health behaviors were also evaluated according to weight, exercise, diet and alcohol consumption patterns before breast cancer diagnosis. MATERIALS AND METHODS: We examined self-reported behavior changes among 1415 women diagnosed with breast cancer in the NIEHS Sister Study cohort. Women reported changes in exercising, eating healthy foods, maintaining a healthy body weight, drinking alcohol, smoking, getting enough sleep, spending time with family and friends, and participating in breast cancer awareness events. RESULTS: On average, women were 3.7 years from their breast cancer diagnosis. Overall, 20-36% reported positive changes in exercise, eating healthy foods, maintaining a healthy weight, or alcohol consumption. However, 17% exercised less. With each 5-year increase in diagnosis age, women were 11-16% less likely to report positive change in each of these behaviors (OR = 0.84-0.89; p < 0.05), except alcohol consumption (OR = 0.97; CI: 0.81, 1.17). Women who underwent chemotherapy were more likely to report eating more healthy foods (OR = 1.47; 95% CI 1.16-1.86), drinking less alcohol (OR = 2.01; 95% CI: 1.01, 4.06), and sleeping enough (OR = 1.41; 95% CI: 1.04, 1.91). The majority of women (50-84%) reported no change in exercise, eating healthy foods, efforts to maintain a healthy weight, alcohol consumption, sleep patterns, or time spent with family or friends. CONCLUSIONS: Many women reported no change in cancer survivorship guideline-supported behaviors after diagnosis. Positive changes were more common among younger women or those who underwent chemotherapy. |
Factors related to pertussis and tetanus vaccination status among foreign-born adults living in the United States
Sanchez-Gonzalez L , Rodriguez-Lainz A , O'Halloran A , Rowhani-Rahbar A , Liang JL , Lu PJ , Houck PM , Verguet S , Williams WW . J Community Health 2016 42 (3) 573-582 Pertussis is a common vaccine-preventable disease (VPD) worldwide. Its reported incidence has increased steadily in the United States, where it is endemic. Tetanus is a rare but potentially fatal VPD. Foreign-born adults have lower tetanus-diphtheria-pertussis (Tdap) and tetanus-diphtheria (Td) vaccination coverage than do U.S.-born adults. We studied the association of migration-related, socio-demographic, and access-to-care factors with Tdap and Td vaccination among foreign-born adults living in the United States. The 2012 and 2013 National Health Interview Survey data for foreign-born respondents were analyzed. Multivariable logistic regression was conducted to calculate prevalence ratios and 95% confidence intervals, and to identify variables independently associated with Tdap and Td vaccination among foreign-born adults. Tdap and Td vaccination status was available for 9316 and 12,363 individuals, respectively. Overall vaccination coverage was 9.1% for Tdap and 49.8% for Td. Younger age, higher education, having private health insurance (vs. public insurance or uninsured), having visited a doctor in the previous year, and region of residence were independently associated with Tdap and Td vaccination. Among those reporting a doctor visit, two-thirds had not received Tdap. This study provides further evidence of the need to enhance access to health care and immunization services and reduce missed opportunities for Tdap and Td vaccination for foreign-born adults in the United States. These findings apply to all foreign-born, irrespective of their birthplace, citizenship, language and years of residence in the United States. Addressing vaccination disparities among the foreign-born will help achieve national vaccination goals and protect all communities in the United States. |
Estrogen-related genes and their contribution to racial differences in breast cancer risk.
Reding KW , Chen C , Lowe K , Doody DR , Carlson CS , Chen CT , Houck J , Weiss LK , Marchbanks PA , Bernstein L , Spirtas R , McDonald JA , Strom BL , Burkman RT , Simon MS , Liff JM , Daling JR , Malone KE . Cancer Causes Control 2012 23 (5) 671-81 ![]() Racial differences in breast cancer risk, including the risks of hormone receptor subtypes of breast cancer, have been previously reported. We evaluated whether variation in genes related to estrogen metabolism (COMT, CYP1A1, CYP1B1, CYP17A1, CYP19A1, ESR1, GSTM1, GSTP1, GSTT1, HSD17B1, SULT1A1, and UGT1A1) contributes to breast cancer risk and/or racial differences in risk within the CARE study, a multi-centered, population-based case-control study of breast cancer. Genetic variation was assessed as single nucleotide polymorphisms (SNPs), haplotypes, and SNP-hormone therapy (HT) interactions within a subset of 1,644 cases and 1,451 controls, including 949 Black women (493 cases and 456 controls), sampled from the CARE study population. No appreciable associations with breast cancer risk were detected for single SNPs or haplotypes in women overall. We detected SNP-HT interactions in women overall within CYP1B1 (rs1800440; p (het)=0.003) and within CYP17A1 (rs743572; p (het)=0.009) in which never users of HT were at a decreased risk of breast cancer, while ever users were at a non-significant increased risk. When investigated among racial groups, we detected evidence of an SNP-HT interaction with CYP1B1 in White women (p value=0.02) and with CYP17A1 in Black women (p value=0.04). This analysis suggests that HT use may modify the effect of variation in estrogen-related genes on breast cancer risk, which may affect Black and White women to a different extent. |
Low-density microarrays for the detection of Borrelia burgdorferi s.s. (the Lyme disease spirochete) in nymphal Ixodes scapularis
Houck JA , Hojgaard A , Piesman J , Kuchta RD . Ticks Tick Borne Dis 2011 2 (1) 27-36 ![]() Lyme disease is the most common tick-borne disease in Europe and North America. In the hyperendemic Lyme disease regions of the eastern United States, nymphal Ixodes scapularis are the principal ticks transmitting the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (s.s.). Approximately 25% of questing nymphs in endemic regions are infected with spirochetes. High throughput-sensitive and specific methods for testing nymphal I. scapularis for infection with B. burgdorferi are clearly needed. In the current study, we evaluated whether low-density microarrays could be adapted for the rapid and accurate detection and characterization of spirochetes in nymphal I. scapularis. Three different microarray platforms were developed and tested for the detection of spirochetes in ticks. They could both detect and differentiate different Borrelia genospecies, in one case detecting as few as a single copy of Borrelia DNA. 2010 Elsevier GmbH. |
MChip, a low density microarray, differentiates among seasonal human H1N1, North American swine H1N1, and the 2009 pandemic H1N1
Heil GL , McCarthy T , Yoon KJ , Liu S , Saad MD , Smith CB , Houck JA , Dawson ED , Rowlen KL , Gray GC . Influenza Other Respir Viruses 2010 4 (6) 411-416 ![]() ![]() BACKGROUND: The MChip uses data from the hybridization of amplified viral RNA to 15 distinct oligonucleotides that target the influenza A matrix (M) gene segment. An artificial neural network (ANN) automates the interpretation of subtle differences in fluorescence intensity patterns from the microarray. The complete process from clinical specimen to identification including amplification of viral RNA can be completed in <8 hours for under US$10. OBJECTIVES: The work presented here represents an effort to expand and test the capabilities of the MChip to differentiate influenza A/H1N1 of various species origin. METHODS: The MChip ANN was trained to recognize fluorescence image patterns of a variety of known influenza A viruses, including examples of human H1N1, human H3N2, swine H1N1, 2009 pandemic influenza A H1N1, and a wide variety of avian, equine, canine, and swine influenza viruses. Robustness of the MChip ANN was evaluated using 296 blinded isolates. RESULTS: Training of the ANN was expanded by the addition of 71 well-characterized influenza A isolates and yielded relatively high accuracy (little misclassification) in distinguishing unique H1N1 strains: nine human A/H1N1 (88.9% correct), 35 human A/H3N2 (97.1% correct), 31 North American swine A/H1N1 (80.6% correct), 14 2009 pandemic A/H1N1 (87.7% correct), and 23 negative samples (91.3% correct). Genetic diversity among the swine H1N1 isolates may have contributed to the lower success rate for these viruses. CONCLUSIONS: The current study demonstrates the MChip has the capability to differentiate the genetic variations among influenza viruses with appropriate ANN training. Further selective enrichment of the ANN will improve its ability to rapidly and reliably characterize influenza viruses of unknown origin. |
Viral shedding and clinical illness in naturally acquired influenza virus infections
Lau LL , Cowling BJ , Fang VJ , Chan KH , Lau EH , Lipsitch M , Cheng CK , Houck PM , Uyeki TM , Peiris JS , Leung GM . J Infect Dis 2010 201 (10) 1509-16 BACKGROUND: Volunteer challenge studies have provided detailed data on viral shedding from the respiratory tract before and through the course of experimental influenza virus infection. There are no comparable quantitative data to our knowledge on naturally acquired infections. METHODS: In a community-based study in Hong Kong in 2008, we followed up initially healthy individuals to quantify trends in viral shedding on the basis of cultures and reverse-transcription polymerase chain reaction (RT-PCR) through the course of illness associated with seasonal influenza A and B virus infection. RESULTS: Trends in symptom scores more closely matched changes in molecular viral loads measured with RT-PCR for influenza A than for influenza B. For influenza A virus infections, the replicating viral loads determined with cultures decreased to undetectable levels earlier after illness onset than did molecular viral loads. Most viral shedding occurred during the first 2-3 days after illness onset, and we estimated that 1%-8% of infectiousness occurs prior to illness onset. Only 14% of infections with detectable shedding at RT-PCR were asymptomatic, and viral shedding was low in these cases. CONCLUSIONS: Our results suggest that "silent spreaders" (ie, individuals who are infectious while asymptomatic or presymptomatic) may be less important in the spread of influenza epidemics than previously thought. |
Effects of oseltamivir treatment on duration of clinical illness and viral shedding and household transmission of influenza virus
Ng S , Cowling BJ , Fang VJ , Chan KH , Ip DK , Cheng CK , Uyeki TM , Houck PM , Malik Peiris JS , Leung GM . Clin Infect Dis 2010 50 (5) 707-14 BACKGROUND: Large clinical trials have demonstrated the therapeutic efficacy of oseltamivir against influenza. We assessed the indirect effectiveness of oseltamivir in reducing secondary household transmission in an incident cohort of influenza index patients and their household members. METHODS: We recruited index outpatients whose rapid test results were positive for influenza from February through September 2007 and January through September 2008. Household contacts were followed up for 7-10 days during 3-4 home visits to monitor symptoms. Nose and throat swabs were collected and tested for influenza by reverse-transcription polymerase chain reaction or viral culture. RESULTS: We followed up 384 index patients and their household contacts. Index patients who took oseltamivir within 24 h of symptom onset halved the time to symptom alleviation (adjusted acceleration factor, 0.56; 95% confidence interval [CI], 0.42-0.76). Oseltamivir treatment was not associated with statistically significant reduction in the duration of viral shedding. Household contacts of index patients who had taken oseltamivir within 24 h of onset had a nonstatistically significant lower risk of developing laboratory-confirmed infection (adjusted odds ratio, 0.54; 95% CI, 0.11-2.57) and a marginally statistically significant lower risk of clinical illness (adjusted odds ratio, 0.52; 95% CI, 0.25-1.08) compared with contacts of index patients who did not take oseltamivir. CONCLUSIONS: Oseltamivir treatment is effective in reducing the duration of symptoms, but evidence of household reduction in transmission of influenza virus was inconclusive. |
Factors affecting QuickVue Influenza A + B rapid test performance in the community setting
Cheng CK , Cowling BJ , Chan KH , Fang VJ , Seto WH , Yung R , Uyeki TM , Houck PM , Peiris JS , Leung GM . Diagn Microbiol Infect Dis 2009 65 (1) 35-41 Rapid diagnosis of influenza can facilitate timely clinical management. We evaluated the performance of the QuickVue Influenza A + B test (Quidel, San Diego, CA) in a community setting and investigated the factors affecting test sensitivity. We recruited 1008 subjects from 30 outpatient clinics in Hong Kong between February and September 2007. Each subject provided 2 pooled pairs of nose and throat swabs; 1 pair was tested by the QuickVue rapid test on site, and the other pair was sent to a laboratory for reference tests. Among 998 enrolled subjects with valid results, the rapid test had overall sensitivity of 0.68 and specificity of 0.96 compared with viral culture. Sensitivity for both influenza A and B was significantly higher for specimens with viral loads greater than 5 log(10) copies/mL. The QuickVue Influenza A + B test has similar sensitivity in point-of-care community settings to more controlled conditions. |
Facemasks and hand hygiene to prevent influenza transmission in households: a randomized trial
Cowling BJ , Chan KH , Fang VJ , Cheng CK , Fung RO , Wai W , Sin J , Seto WH , Yung R , Chu DW , Chiu BC , Lee PW , Chiu MC , Lee HC , Uyeki TM , Houck PM , Peiris JS , Leung GM . Ann Intern Med 2009 151 (7) 437-46 BACKGROUND: Few data are available about the effectiveness of nonpharmaceutical interventions, such as hand hygiene and facemasks, for preventing influenza virus transmission. OBJECTIVE: To investigate whether hand hygiene and use of facemasks prevents household transmission of influenza. DESIGN: Cluster randomized controlled trial. Randomization was computer generated; allocation was concealed from treating physicians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. SETTING: Households in Hong Kong. PATIENTS: 407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households. INTERVENTION: Lifestyle education (control) (134 households), hand hygiene (136 households), or surgical facemasks plus hand hygiene (137 households) for all household members. MEASUREMENTS: Influenza virus infection in household contacts, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) or diagnosed clinically after 7 days. RESULTS: Sixty (8%) household contacts in the 259 households had RT-PCR-confirmed influenza virus infection in the 7 days after intervention. Hand hygiene without or with facemasks seemed to reduce influenza transmission, but the differences in transmission compared with the control group were not statistically significant. In 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR-confirmed infection seemed to be reduced, an effect attributable to reductions in infection among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]). Adherence to interventions was variable. Limitation: The delay from index patient symptom onset to intervention and variable adherence may have mitigated intervention effectiveness. CONCLUSION: Hand hygiene and facemasks seemed to prevent household transmission of influenza virus when implemented within 36 hours of index patient symptom onset. These findings suggest that nonpharmaceutical interventions are important for mitigation of pandemic and interpandemic influenza. Primary Funding Source: Centers for Disease Control and Prevention. |
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